have to agree it was fairly straight forward in that you knew people turned into monsters and you also saw the riders were beta testing the drivers then everything goes nuts and it turns into the battle of the upgrades to see who can upgrade faster

Changerion didn't have a motif. He had a common color scheme between his personal weapons, which they themselves didn't really have a theme to, but he himself didn't really have a motif. I guess you could debate that his motif is alien-esque technology but that's kind of a stretch.